The present invention is directed to a drill fixture useful for drilling holes in or through relatively small bead like objects such as pearls or semi precious stones, for stringing into necklaces, etc., or for mounting upon metal pins. The fixture is especially intended for use in jewelry production or repair.
Drilling of holes into or through pearls presents certain problems not generally encountered when drilling metal objects. Natural pearls are only approximately spherical and are composed of a relatively soft organic substance which is susceptible to marring during the drilling operation. If the pearl is held or clamped too tightly during the drilling operation, its surface will be marred by the excessive pressure applied by the clamp, if the pearl is not held tightly enough, it will spin within the clamp, again resulting in marring of its surface. It is thus quite common in the jewelry industry to manually hold the pearl in position during the drilling operation, particularly when more valuable pearls are being drilled, to avoid the possibility of marring the surface.
However, manually holding the pearl during the drilling operation does not completely eliminate the problem of marring the surface of the pearl, particularly where a bore must extend entirely through the pearl, as in the situation where the pearl is being prepared for stringing into a necklace. The pearl is extremely susceptible to chipping and flaking as the drill tip passes through the pearl surface in completing the through bore. This particular problem can be overcome by drilling the bore part way through the pearl from one side and then inverting the pearl and drilling the remainder of the bore from the opposite side of the pearl. However, this procedure obviously calls for an extremely high degree of precision in locating and aligning the pearl for the second step of the two step drilling operation.
Chipping also tends to occur when the hole through the pearl is redrilled to enlarge the hole, as for the assembly of latch findings at the ends of the pearl strings.